Dream Riddle

I had a dream today ("last night") which had a riddle in it. The dream was mostly Wizard of Oz themed; yellow brick road, munchkins, wizard etc. So I was waiting to see the wizard, I forget why. However, when I was allowed to see the Wizard I had to answer a riddle before he would answer my question. It seemed like in my dream I knew the answer and it was on the tip of my tongue but I couldn't quite get it. In the dream it seemed as if the riddle was very familiar. From one of the Oz books I have read?

The Wizard looked tall and menacing. He looked like a dark Pinocchio in the face and had long fingers that looked like black sticks which he wiggled at me as he told me the riddle in a haunting voice:

"If you know me, you know my name; and it is the average conjecture on everyone's tongue."

Interestingly, the dream itself wasn't very scary.